The integration of electronic circuits raises, apart from other problems, that of embodying electric connections between the integrated circuit and the outside world. This technique concerning connections is nowadays known under the term of "connection processing". The more the integration density increases, the larger are the number of inputs/outputs required and the more difficult is the problem concerning connection processing.
There currently exist a number of techniques making it possible to establish these connections, such as the TAB technique ("Tape Automated Bonding" technique). It consists of forming conductive blocks, distributed around the active zone of the chip and connected to the electronic circuits installed in the latter, and being welded to conductive tabs on these conductive blocks.
A detailed description of this technique appears in the publication published by S.M. SZE and entitled "VLSI Technology", McGraw-Hill International Book Company.
In certain cases, especially for circuits having a high integration density, it is preferable to avoid using intermediate links but make use of the COG ("Chip On Glass" technique or even the COX ("Chip On X") technique. According to this technique, the chip is mounted, by multiple bondings or soldering joints by remelt heating, directly on the glass support (or on the ceramic support or any other compatible material, including the special printed circuits).
For a given integrated circuit, the type of connection processing is determined in advance and embodied during the method for embodying the circuit. The metallic blocks are produced during the final production operations, especially during a metallization operation. A passivation film (of oxides, nitrides, polyamides or other substances) is then deposited on the unit and, by means of etching, the conductive blocks are freed so that the connections can next be made.
The applications of a given integrated circuit are thus determined, not merely by the electronic functions fulfilled by this circuit, but also by the selected connection processing. Here, there is a single limitation to the extent that an integrated circuit with given electronic functions could in certain cases be used for other applications if it has another connection processor (such as a COG connection processor instead of a TAB connection processor).